1. Field of the Invention
The present invention relates to a multi-layer build-up system for floor coverings when using floor heating systems, particularly for laying ceramic floor coverings using the thin-bed method.
2. The Prior Art
Ceramic floor coverings and tiles, in particular, are usually laid using the so-called thin-bed method, in which the ceramic floor coverings are laid into a thin adhesive layer consisting of a tile mortar. This method, which is satisfactory for normal substrates such as walls or screed, has disadvantages when laying ceramic floor coverings on floor heating systems, also called radiant heating systems, in that the ceramic floor covering is subject to special stresses because the conditions of the substrate are constantly changing due to the thermal stresses of the floor heating system. Therefore, a cast plaster screed is usually applied over floor heating systems, which screed is usually so thick that the screed can serve as a stable substrate for the ceramic floor covering, and is uncoupled from the varying expansion conditions in the region of the pipes of the floor heating system. For this purpose, a thickness of the screed of generally more than 45 mm, and usually more than 60 mm, is required, and this has the result that the floor structure is very high because of the floor heating system, the screed, and the ceramic floor covering. Here, it is difficult to have a total thickness of less than 100 mm, and therefore such floor heating systems tend to be used rather rarely, particularly in renovations. In addition, particularly in renovations, when wood floors are being renovated, for example, such substrates are not resistant to bending in and of themselves, but rather demonstrate corresponding deformability and elasticity, which is an additional disadvantage for laying ceramic floor tiles. Also, because of the differing expansion coefficients of substrate, thin-bed mortar, and ceramic floor covering resulting from the thermal stress due to the floor heating, it is difficult to manage the cracking behavior of the ceramic floor covering and the substrate. Therefore, cracks frequently occur in the tile floor covering, if the tile floor covering is firmly connected with the substrate.
Floor heating systems are known, and described, for example in German Patent Nos. DE 87 03 642 U1 and DE 81 07 402 U1, in which plate-shaped components of foamed materials such as Styrofoam or the like are used as a substrate and for accommodating the pipelines for the heating fluid, in which components grooves are provided for accommodating the pipelines. The plate-shaped components are laid at the laying location and therefore offer insulation of the floor heating system in a downward direction and accommodation channels for the pipelines systematically arranged over the laying area, by the grooves. For better distribution of the heat passed to the laying area by the pipelines, heat conduction elements in the form of heat-conductive sheets or the like, which are in heat-conductive contact with the pipelines, at least in sections, are provided on the top of the plate-shaped components. In order to apply a ceramic floor covering on substrates in a secure manner and free of cracks for the long term, it is necessary to cast a relatively thick screed layer onto the heat-conductive sheets and allow it to harden. Aside from the problem of the time-consuming hardening phase of the screed, such a floor structure having a thick screed layer has the disadvantage that the floor heating system reacts relatively slowly, since the thick screed layer always has to be heated up first, before useful heat can be introduced into the space that lies above it. Especially during transitional seasons or in the case of constantly changing need for heat, this is a disadvantage.